Magnetostrictive light valve



March 13, 1934?. r w. J. HERDMAN 1,951,018

MAGNETOSTRICTIVE LIGHT VALVE Filed Nov. 1, 1950 ELEMJ...

INVENTOR Patented Mar. 13, 1934 MAGNETOSTRICTIVE LIGHT VALVE William J.Herdman, South Orange, N. J., assignor to Wired Radio, Inc., New York,N. Y., a

corporation of Delaware Application November 1, 1930, Serial No.492.7331

3 Claims.

My invention pertains in general to light valves and specificallyrelates to'a light valve operated by magnetostriction.

It has been found that ferromagnetic substances, particularly nickel andnickel-steel alloys, evidence a mechanical deformation under theinfluence of a magnetic field. This phenomenon is sometimes referred toas the Joule effect, being named for Joule, who made earlyinvestigations in magnetostriction. Certain ferromagnetic metals-possessmore marked magnegostrictive properties than others. I have found that asteel alloy containing 46 percent of nickel exhibits a marked mechanicalexpansion when magnetized; on the other hand, pure nickel exhibitsmechanical contraction when magnetized. In United States Patent No.1,467,318, issued to me September 11, 1923, and entitled Electrondischarge device, I have disclosed the 0 use of such magnetostrictiveelements in a novel type of electron discharge device. Mypresentinvention is directed to controlling, by means ofmagnetostriction, a light beam incident upon a photosensitive device.

One of the objects of my invention consists in providing a light valveemploying magnetostrictive means to control a light beam in accordancewith an alternating or other variable current.

1 Another object of my invention consists in providing an arrangement oflight valve in which a imagnetostrictive element is interposed between asource of light and photosensitive means.

A further object comprises producing means for controlling the intensityof alight beam incident upon photosensitive means in accordance withacoustical vibrations.

I accomplish the above desirable objects in a novel type of light valveunder control of mechanical dilations produced by ferromagneticsubstances in amagnetic field,,

- In the drawing which accompanies and forms a part of thisspecification and in which like reference numerals designatecorresponding parts throughout:

Fig. 1 is a schematic representation of one embodiment of the lightvalve of my invention;

Fig. 2 is a schematic representation of an alternative arrangement ofthe light valve of Fig. 1;

Fig. 3 is a representation of another form of The screen 1 is opaque andis provided with an aperture 4 adapted to direct a beam of light fromthe light source 2 upon the photosensitive cathode of the photoelectriccell 3. The output of the photoelectric cell 3 is directed to anamplifier 5 0 having output terminals 6. The amplifier 5 may be of anyconventional type adapted to amplify photoelectric currents, such as aresistancecoupled multi-stage thermionic amplifier. A battery 11 isprovided as a source of current for the 5 light source 2. v 1

According to my invention, two ferromagnetic rods 7 and 8 are disposedupon opposite sides of the beam of light defined by aperture 4 in thescreen 1. These rods 7 and 8 are preferably composed of an alloy whichexhibits pronounced magnetostrictive properties, such as the steelalloyed with. 46 percent of nickel previously mentioned. A winding isprovided around each of the rods 7 and8 toproduce a magnetic field.These windings are" connected in series to a battery 9 and a microphone10. Sound waves incident upon the microphone 10 control the" intensityof the magnetic fields produced by the windings around the rods 7 and 8.The rods '7 and 8 are positioned 0 with reference to the light beam'from the aperture 4 in a manner such that the magnetostrictive dilationsof the rods 7 and 8 intercept the light beam in accordance with thefluctuations of the magnetic field under control of the microphone 1 0.35 Variations in the intensity of the light beam thus brought aboutcorrespondingly affect the output of the photoelectric cell 3 to producea modulating current at the output terminals 6 of the amplifier 5 inaccordance with the fluctuations in the currentfrom the battery 9 undercontrol of the microphone 10.

Fig. 2 is an alternative arrangement of my light valve in which aphotographic film is substituted, for the photoelectric cell of Fig. 1,as the photosensitive means under control of light rays from the lightsource 2. Inthis arrangement, a photographic film 12 is provided betweentwo reels 13 and 14. A motor 15 is mechanically coupled to the reel 13and is adapted to longitudinally move the film 12 in the directionindicated by the arrow. The magnetostrictive dilation of the rods 7- and8 control the light beam from the aperture 4 to produce a record, on thefilm 12, of the variations of current under control of the microphone10. Such a record is, in effect, a record of the sopnd waves incidentupon the microphone 10 and may be used for sound reproduction purposes,such as in sound moving pictures. The elements shown in Fig. 2correspond to similar elements that the ends 1'; and 18 are injuxtaposition to control a light beam passing between the ends inaccordance with a, magnetic field applied to the core 16. The core 16 ispreferably composed of a nickel-steel alloy, such as used for the rods'7 and 8. A winding isprovided about the'core 16 and is connected inseries with battery 9 and(microphone 10. The magnetic field produced bythe winding about the toroidal core 16 produces a mechanical dilation ofthe core in ccordance with the intensity of themagnetic fiel in a mannersuch as to control the intensity of the beam of light passing betweenthe core ends 1'7. and 18.

The intensity of the magnetic field is under control of the microphone10, as in Figs. 1 and 2.

Fig. 4 illustrates still another form of the light valve of my inventionwhich may be used in either thesystem of Fig. 1 or the system of Fig. 2.In Fig. 4, two metallic strips 19 and 20 are positioned, respectively,adjacent to the metallic strips 21 and 22. The metallic strips 19 and 20are composed of the nickel-steel alloy previously mentioned, and expandwhen under the influence of a magnetic field. The strips 21 and 22 arecomposed of nickel which contracts when under the influence of amagnetic field. The pair of strips 19 and 21 and the pair of strips 20and 22 are rigidly mounted at opposite ends of a base member 23. Twoopaque members 24 and 25 are securely mounted on the strips19 and 21,and on the strips 20 and 22, respectively,-as'shown. A

Y winding 26 is provided about the strips 19 and 21 and connected inseries with another winding 27 provided about the strips 20 and 22. Thewind-.

ings 26 and 2'7 are connected in series with a battery 28 and a rheostat32 is provided to regulate the intensity of the permanent field. Anotherwinding 29,is provided about thestrips 19 and 21 and is connected inseries with a -winding 30provided about the strips 20 and 22. Thewindings 29 and 30 are connected in series with a battery9 2p andwindings 26 and 2'7, and rheostat 32, provide a steady magnetic field ofselected intensity acting upon the pair of strips 19 and 21 and the pairof strips 20 and 22, respectively. The action of the strips 19-and 20 toexpand under the influence of a magnetic field, while the action of thestrips 21 and 22 is to contract when under the influence .of a magneticfield. The additive effects of the mechanical expansion and contractionin each of the pairs, therefore, causes the members 24 and 25 to be.moved in the direction of the arrows when under the influence of anincreasing magnetic field. The windings 29 and 30 produce magneticfields varying in intensity in accordance .with sound waves incidentupon the microphone 10.. This alternating field produced by the coils 29and 30 acts upon the steady field produced by the windings 26 and 2'7 toaccentuate the current variations produced by the microphone 10 in awell known manner. The members 24 and 25 are therefore moved to and fromeach other to intercept a beam of light directed between the ends of themembers 21 and'25 in accordance with. sound waves impinged upon themicrophone 10.

It'will now be obvious that I have provided a novel form of light valveoperated upon the magnetorestrictive principle and which provides a newmethod for controlling a light beam. It will of course be understoodthat changes in the form of my invention will readilf occur to thoseskilled in the art, but which will not depart from v the intended scope.of my invention. I do not, therefore, desire to limit myself to theforegoing except insofar as may be pointed out in the appended claims.What I claim as new and original and desire to secure by Letters Patentof the United States is:

. 1. .In a light valve for controlling a beam of light, means forproducing a-controlled electromagnetic field, a pair of bl-metallicmembers flexibly extending from a rigid support, said members eachcomprising an element of magnetostrictively expansible material and anelement of magnetostrictively contractable material co-acting to producean accentuated flexure, and shutter elements moved by said bi- 110metallic members for affecting said beam of light, saidbi-metallic'members being mounted to produce respectively opposedfiexure under them-'- fiuence ofsaid-field whereby the movement of saidshutter elements produces an additive con trolling effect upon said beamof light.-

2. In a light valvefor controlling a beam of light incident uponphotosensitive means means for producing a controlled magnetic f ld, and

magnetostrictively operable members mounted 120 within said field andwith their corresponding extremities positioned so that they may overlapfor movement in the path of said lightbeam to -control the amountof'light falling upon said photosensitive means by magnetostrictivedilation of said-members under control of said electromagnetic field. 1p

3. Ina light valve for controlling a beam of light incident uponphotosensitive means, means for producing a controlled magnetic field,and a 130 plurality of,me bers composed of magnetostrice tively activema erial with said field, each havin one extremitythereof rigidlymounted and the other extremities disposed so that they may over-- lapin the path of said light beam whereby the magnetostrictive dilation ofsaid members under influence of said field produces an interceptingefiect on said beam of light.

. r WILLIAM J. HERDMAN.

